Abstract

Translating noisy sensory signals to perceptual decisions is critical for successful interactions in complex environments. Learning is known to improve perceptual judgments by filtering external noise and task-irrelevant information. Yet, little is known about the brain mechanisms that mediate learning-dependent suppression. Here, we employ ultra-high field magnetic resonance spectroscopy of GABA to test whether suppressive processing in decision-related and visual areas facilitates perceptual judgments during training. We demonstrate that parietal GABA relates to suppression of task-irrelevant information, while learning-dependent changes in visual GABA relate to enhanced performance in target detection and feature discrimination tasks. Combining GABA measurements with functional brain connectivity demonstrates that training on a target detection task involves local connectivity and disinhibition of visual cortex, while training on a feature discrimination task involves inter-cortical interactions that relate to suppressive visual processing. Our findings provide evidence that learning optimizes perceptual decisions through suppressive interactions in decision-related networks.

Highlights

  • Translating noisy sensory signals to perceptual decisions is critical for successful interactions in complex environments

  • Our results reveal distinct GABAergic inhibition mechanisms in a cortical network that is known to be involved in perceptual decisions

  • Learning feature differences is implemented by interactions between parietal and visual areas that relate to increased GABAergic inhibition in visual cortex

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Summary

Introduction

Translating noisy sensory signals to perceptual decisions is critical for successful interactions in complex environments. Combining GABA measurements with functional brain connectivity demonstrates that training on a target detection task involves local connectivity and disinhibition of visual cortex, while training on a feature discrimination task involves intercortical interactions that relate to suppressive visual processing. Previous functional magnetic resonance imaging (fMRI) studies have demonstrated learning-dependent changes in functional brain activity due to training on perceptual tasks that involve detecting targets in clutter or discriminating fine feature differences (for reviews[7,8]). The inhibitory brain plasticity mechanisms that support our ability to improve our perceptual decisions by learning to suppress noisy and task-irrelevant information through training remain largely unknown. To test whether learning involves local processing within visual cortex or suppressive interactions between decision-related and sensory areas, we combined GABA measurements in occipito-temporal and posterior parietal cortex with functional brain connectivity, as measured by resting-state fMRI. Our results provide evidence that learning improves perceptual decisions through suppressive interactions within decision-related circuits in the human brain

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